DORAL, Fla. (AP) — Rory McIlroy offered another apology, a straightforward explanation and a pledge Wednesday that he will never again quit in middle of a round.

McIlroy faced the media for the first time since he abruptly walked off the golf course in the second round of the Honda Classic, telling reporters that his head was not in the right place and then issuing a statement that his sore wisdom tooth made it difficult to concentrate.

Turns out the wisdom tooth wasn't the whole truth, and the world's No. 1 player said, "It will never happen again."

"I think it was a buildup of everything," McIlroy said at the Cadillac Championship. "I've been putting a lot of pressure on myself to perform, and I've been working so hard and not really getting much out of it. That's just been the frustrating thing, and that's what happened.

"I just sort of let it all get to me."

McIlroy attributed his frustration to wanting to improve on his breakthrough season, when he won his second major at the PGA Championship, five tournaments around the world, money titles on the two biggest tours and established himself as the best player in golf.

But he dismissed suggestions that his new equipment deal added to the pressure.

The 23-year-old from Northern Ireland signed with Nike for what is said to be upward of $20 million a year. He was introduced as Nike's latest global star with a glitzy laser show in Abu Dhabi, but his game fell apart quickly. He has missed the cut, lost in the opening round of the Match Play Championship and quit after 26 holes of the Honda Classic. That led to speculation that he can't adjust to the new clubs.

"It doesn't make a difference what deal or what clubs I play. That's irrelevant," McIlroy said. "It's about me on the golf course, and the expectations and the pressure that I put myself under."

He also said his poor play has nothing to do with his relationship with tennis star Caroline Wozniacki.

"Just because I have a bad day on the golf course and Caroline loses a match in Malaysia, it doesn't mean that we're breaking up," he said with a laugh. "It's sport. And look, I'd rather keep my private life as private as possible. Everything on that front is great, and I'm looking forward to seeing her next week when she goes to Miami."

It was the first time McIlroy has been criticized, not only for quitting in the middle of the round but trying to disguise the reason as a sore wisdom tooth. He did say his lower right tooth has been bothering him, and that he would see his dentist in Belfast later this year.

"It wasn't bothering me enough to quit," he said.

This was about the frustration of not finding his swing and being exposed on the golf course with high scores.

And it led to a decision he wishes he could take back.

"No matter how bad I was playing, I should have stayed out there," he said. "I should have tried to shoot the best score possible even though it probably wasn't going to be good enough to make the cut. At that point in time, I was just all over the place. I saw red ... and it was a mistake and everyone makes mistakes and I'm learning from them. I guess for me, some people have the pleasure of making mistakes in private. Most of my mistakes are in the public eye.

"I regret what I did."

The good news for McIlroy is that he is assured of playing all four rounds at Doral, where there is no cut. McIlroy is scheduled to play this week and at the Houston Open at the end of the month before going to the Masters. He did not indicate that he would add another tournament despite having played only 80 holes this year.

And while he walked off the golf course last week, McIlroy said he worked for 10 hours at The Bear's Club on Saturday, and almost as much on Sunday. He practiced Monday before going to Seminole for a club event. He said he realized his swing was not the same as it was last year, and the frustration comes from not being able to fix it.

"You just have to get to the root of the problem — no pun intended," he said. "I know if I can get my takeaway fixed, the rest of the swing will follow. I've worked my (tail) off over the last four or five days to really try and get this right. Still, it's a work in progress. As I said, there's no quick fixes in golf but I'm going to go out there this week and all I care about is my swing. And I know if I can get my swing back on track that the results will follow."

McIlroy will play the opening two rounds of this World Golf Championship with Tiger Woods and Luke Donald, a group featuring the top three players in the world. They figure to command all the attention around the Blue Monster.